Print .zpl file direct from website

Hi all,

We are new with using Zebra printers, we have the GK420d.

We are printing on a different brand, but now with the new website back-end and our shipping courrier advices to use a zebra printer and generate labels with a .zpl file we are currently setting it all up

But the problem we have when our back-end generates the .zpl shipping label we cannot print it with the zebra.

Can you help with this.

What is the best way to print it directly?

Hope to get some help.

Merry Christmas!